The vitreous body is a connective tissue with an organized structure. The objective of this proposal is to determine the macromolecular structure and interactions responsible for maintaining this organized structure. We plan to study in detail the structural aspects of the major constituents of the vitreous, such as collagen, hyaluronic acid, and other noncollagenous proteins, and the interrelationships among these macromolecues. In vitro experiments will be performed with preparations obtained from cattle, rabbit, and owl monkey. Whenever possible, the results of these experiments will be correlated with studies carried out on the human vitreous obtained from open-sky vitrectomy. We will use viscosity, sedimentation, electron microscopy, and spectroscopic techniques such as circular dichroism, optical rotation, fluorescence, etc. Since the vitreous body shows a gel-liquid transition in the aging process and also in many eye diseases, studies on the conformational transition or the interaction properties of different components of the vitreous will be monitored by a Differential Scanning Calorimeter.